8 vehicles earn top rating for collision warning
The 2014 Chevrolet Impala is the only non-luxury car to earn the highest rating in tests of high-tech crash prevention systems.
Seven luxury cars have also earned "superior" ratings from the Insurance Institute for Highway Safety when equipped with optional collision warning and automatic braking.
They are the BMW 5 Series, BMW X5, Mercedes-Benz E-Class, Buick Regal, Cadillac CTS, Cadillac XTS and 2015 Hyundai Genesis.
To get the highest rating, vehicles must warn drivers of impending collisions and apply automatic brakes to significantly slow the speed. Tests are conducted at 12 miles per hour and 25 mph.
The institute, which is funded by insurers, says 40 percent of 2014 models now offer forward collision warning, while 20 percent offer automatic braking. The results may encourage wider adoption of the technology.